Haematococcus pluvialis caleosin has the function of stabilizing oil bodies. In order to investigate its physical and chemical characteristics and functions, the full-length cDNA sequence of cleosin gene of H. pluvialis was obtained by the method of combining homologous cloning and RACE amplification technology, and by the bioinformatics analysis, HaeClo gene expression analysis was conducted. The analysis showed that HaeClo was 1 088 bp in length, encoding a total of 262 amino acids, and the theoretical isoelectric point of 7.73. BLAST homology comparison revealed that the amino acid sequence of HaeClo had 66% and 61% similarity to caleosin derived from Gonium pectorale and Chlamydomonas reinhardtii, re-spectively, which was a typical caleosin family member. The analysis of multiple alignment and phylogenetic tree showed that caleosin derived from higher plants and lower plants may come from a common ancestor. Under di.erent stress conditions, the expression level of the HaeClo gene reached the highest value on the third day of culture. At this time, the expression level of the high blue light+1/4 nitrogen treatment group reached the peak, and the expression level of the high white light+1/4 nitro-gen treatment group was the second. And the target protein was successfully expressed in E. coli. In this study, the gene se-quence encoding caleosin in H. pluvialis was obtained.rstly, and subjected to bioinformatics analysis, expression analysis of H. pluvialis under di.erent stress conditions of high light and nitrogen de.ciency, and further study of HaeClo gene expres-sion in H. pluvialis,which laid the foundation for the expression and function of caleosin in H. pluvialis.